66666678 has 64 divisors (see below), whose sum is σ = 150528000. Its totient is φ = 19543680.

The previous prime is 66666667. The next prime is 66666683. The reversal of 66666678 is 87666666.

It is a happy number.

It is a Curzon number.

It is a plaindrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 66666678.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 190848 + ... + 191196.

It is an arithmetic number, because the mean of its divisors is an integer number (2352000).

Almost surely, 2^66666678 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66666678, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (75264000).

66666678 is an abundant number, since it is smaller than the sum of its proper divisors (83861322).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66666678 is a wasteful number, since it uses less digits than its factorization.

66666678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 477.

The product of its digits is 2612736, while the sum is 51.

The square root of 66666678 is about 8164.9665032993. The cubic root of 66666678 is about 405.4801560154.

The spelling of 66666678 in words is "sixty-six million, six hundred sixty-six thousand, six hundred seventy-eight".